Catalytic cracking process

ABSTRACT

A catalytic cracking process is disclosed using a catalyst comprising a framework dealuminate Y zeolite, which is rare earth and aluminum exchanged.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of copending application Ser. No. 140,872, filed onJan. 6, 1988, and now U.S. Pat. No. 4,880,787. Application Ser. No.140,872 is a continuation-in-part of Ser. No. 897,000, filed Aug. 15,1986, and now abandoned, relied upon and incorporated by referenceherein.

FIELD OF THE INVENTION

The invention is directed to a new catalyst composition based onframework dealuminated faujasitic zeolites, to its preparation and toits use in catalytic cracking.

BACKGROUND OF THE INVENTION

Naturally occurring and synthetic zeolites have been demonstrated toexhibit catalytic properties for various types of hydrocarbonconversions. Certain zeolites are ordered porous crystallinealuminosilicates having definite crystalline structure as determined byx-ray diffraction. Such zeolites have pores of uniform size which areuniquely determined by the structure of the crystal. The zeolites arereferred to as "molecular sieves" because the uniform pore size of thezeolite material allows it to selectively sorb molecules of certaindimensions and shapes.

By way of background, one authority has described the zeolitesstructurally, as "framework" aluminosilicates which are based on aninfinitely extending three-dimensional network of AlO₄ and SiO₄tetrahedra linked to each other by sharing all of the oxygen atoms.Furthermore, the same authority indicates that zeolites may berepresented by the empirical formula:

    M.sub.2/n O.Al.sub.2 O.sub.3.xSiO.sub.2.yH.sub.2 O

In the empirical formula, M was described therein to be sodium,potassium, magnesium, calcium, strontium and/or barium; x is equal to orgreater than 2, since AlO₄ tetrahedra are joined only to SiO₄tetrahedra, and n is the valence of the cation designated M; and theratio of the total of silicon and aluminum atoms to oxygen atoms is 1:2.D. Breck, ZEOLITE MOLECULAR SIEVES, John Wiley & Sons, N.Y., p.5 (1974).

The prior art describes a variety of synthetic zeolites. These zeoliteshave come to be designated by letter or other convenient symbols, asillustrated by zeolite A (U.S. Pat. No. 2,882,243); zeolite X (U.S. Pat.No. 2,882,244); zeolite Y (U.S. Pat. No. 3,130,007); zeolite ZK-5 (U.S.Pat. No. 3,247,195); zeolite ZK-4 (U.S. Pat. No. 3,314,752); zeoliteZSM-11 (U.S. Pat. No. 3,709,979) and zeolite ZSM-23 (U.S. Pat. No.4,076,842), merely to name a few.

The particular faujasitic or Y-type zeolite utilized in this inventionhas come to be known as ultrastable Y (USY) and is sometimes referred toas dealuminated Y (DAY). A partial list of references describing thenature and methods of preparation of USY or DAY, all of which areincorporated herein by reference are:

1. Maher, P. K., U.S. Pat. No. 3,293,192.

2. Kerr, G. T., J. Phys. Chem., 71: 4155 (1967).

3. McDaniel, C. V., U.S. Pat. No. 3,607,403.

4. Maher, P. K., U.S. Pat. No. 3,402,996.

5. Scherzer, J., "The Preparation and Characterization of AluminumDeficient Zeolites", ACS Symposium Series, Paper No. 10, June 13-16,1983, pp. 157-200.

It is clear from these references, and other scientific and patentliterature that USY is not a single entity but a family of materialsrelated to zeolite Y. USY is similar to zeolite Y in that itscharacteristic x-ray diffraction lines are substantially those ofzeolite Y as detailed in Tables A, B and C of the above referenced U.S.patent and herein incorporated. USY differs from as-synthesized zeoliteY in that by the nature of the various processing schemes and the degreeto which zeolite Y is dealuminated, the effective frameworksilica-to-alumina ratio is increased. One measure of this change isreflected in the measurement of unit cell size of the resultant zeolite,usually reported in the atomic unit, Angstroms (A). As aluminum isremoved from the zeolitic framework, hence causing the zeoliticframework silica-to-alumina ratio to increase, the unit cell sizedecreases. This results because of differences in bond distances betweenAlO₄ tetrahedra and SiO₄ tetrahedra.

U.S. Pat. No. 4,309,280 suggests the use of crystalline zeolites inhydrocarbon conversion processes. Specific processes relating to thecracking of gas oils to produce motor fuels have been described andclaimed in many patents including, for example, U.S. Pat. Nos.3,140,249; 3,140,251; 3,140,252; 3,140,253 and 3,271,418, hereinincorporated by reference. In one or more of the above identifiedpatents the combination of zeolites with a matrix for use in catalyticcracking is suggested.

Other references disclose the use of USY or DAY to crack alkanes. Forexample, A. Corma, et al., in APPLIED CATALYSIS, Vol. 12 (1984), pp.105-116, present a "Comparison of the Activity Selectivity and DecayProperties of LaY and HY Ultrastable Zeolites During the Cracking ofAlkanes". Pine, L. A., et al., in the JOURNAL OF CATALYSIS, Vol. 85(1984), pp. 466-476 present data to support the "Prediction of CrackingCatalyst Behavior by a Zeolite Unit Cell Size Model". The performance ofcracking catalysts containing USY or DAY are often compared to catalystscontaining zeolite Y which has not been intentionally dealuminated.Because of the deleterious effect of sodium on the performance ofcracking catalysts, USY or DAY catalysts are frequently compared withcatalysts containing the hydrogen form of Y zeolite (HY) or the rareearth form of Y zeolite (REY).

In general the patent and scientific literature suggests the followingfor cracking catalysts containing USY or DAY, containing substantiallyno rare earth (Those claims being at constant conversion relative to REYcontaining cracking catalyst): 1. significant increases in gasolineresearch and motor octane (unleaded); 2. significant decreases in cokemake; 3. definitive increases in total C₃ +C₄ make, particularly C₃olefins and C₄ olefins; 4. reductions in gasoline yield.

Furthermore, lower catalytic activity is evidenced with decreasing unitcell size (U.C.S.) of the Y zeolite component. Hence a non-rare earthcontaining USY or DAY zeolite would exhibit lower activity/stabilitythan a non-dealuminated REY zeolite because the former has a lowerU.C.S. both as manufactured and subsequent to equilibration in aconventional cracking unit.

When rare earth components are introduced into these USY or DAYcontaining catalysts (RE-USY), irrespective of whether they arepre-exchanged onto the zeolite or post-exchanged onto the catalyst theincreases in gasoline research and motor octane (unleaded), theincreases in C₃ and C₄ production and the decreases in coke make arediminished in proportion to the amount of rare earth added. Furthermorelower catalytic activity for the RE-USY is still evidenced relative tonon-dealuminated REY.

The catalyst of the present invention as disclosed below performs in asignificantly different manner which was not a priori anticipated.

SUMMARY OF THE INVENTION

The present invention is directed to a catalyst composition comprisingdealuminated faujasitic zeolites composited with a matrix, saidcomposite additionally containing alumina and rare earth oxides.Optionally the catalyst contains weighting agents, which may or may notthemselves possess catalytic activity, and noble metals, rhenium and/orchromium.

The invention is also directed to the method of preparing said catalyst,by compositing a dealuminated faujasitic zeolite and a matrix, saidcomposite being subjected to treatment with a source of aluminum andrare earth compounds and subsequently subjecting said catalyst to one ormore hydrothermal treatments.

Lastly, the invention is directed to the use of the new catalyst incatalytic cracking operations to produce higher gasoline and distillateyields while minimizing the production of coke and C₄ and lighter gasesat lower catalyst useage per barrel of feed by virtue of its superiorhydrothermal stability.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the change in selectivity and gasoline octane,wherein the gasoline yield, C₄ and lighter gases, coke, light fuel oiland gasoline research octane clear are plotted against the volumepercent conversion of a gas oil to gasoline, lighter components and cokefor the catalyst of the present invention and compared with the resultsobtained under identical conditions for a conventional REY crackingcatalyst.

FIG. 2 shows the effect of rare earth level on the hydrothermalstability of the catalyst of the present invention, wherein volumepercent conversion of a gas oil to gasoline, lighter components and cokeis shown as a function of increasingly severe hydrothermal deactivation,at various rare earth contents.

DETAILED DESCRIPTION OF THE INVENTION

Conventional cracking catalysts generally contain amorphoussilica-alumina or crystalline aluminosilicates. Other materials said tobe useful as cracking catalysts are the crystallinesilicoaluminophosphates of U.S. Pat. No. 4,440,871 and the crystallinemetal aluminophosphates of U.S. Pat. No. 4,567,029.

However, the major conventional cracking catalysts presently in usegenerally incorporate a large pore crystalline aluminosilicate zeoliteinto a suitable matrix component which may or may not itself possesscatalytic activity. These zeolites typically possess an averagecrystallographic pore dimension of about 7 angstroms and above for theirmajor pore opening. Representative crystalline aluminosilicate zeolitecracking catalysts of this type include zeolite X, zeolite Y, zeoliteZK-5, zeolite ZK-4, hereinabove referenced, as well as naturallyoccurring zeolites such as chabazite, faujasite, mordenite, and thelike. Also useful are the silicon-substituted zeolites described in U.S.Pat. No. 4,503,023. Zeolite Beta (U.S. Pat. No. 3,308,069) is yetanother large pore crystalline aluminosilicate which can be utilized incatalytic cracking.

The catalyst compositions of this invention comprise four essentialcomponents: framework dealuminated faujasitic zeolites; a matrix;aluminium compounds; and, rare earth compounds.

In general, the crystalline zeolites are ordinarily ion exchanged eitherseparately or in the final catalyst with a desired cation to replacealkali metal present in the zeolite. The exchange treatment is such asto reduce the alkali metal content of the final catalyst to less thanabout 1.5 weight percent and preferably less than about 1.0 weightpercent. The purpose of ion exchange is to substantially remove alkalimetal cations which are known to be deleterious to cracking, as well asto introduce particularly desired catalytic activity by means of thevarious cations used in the exchange medium. For the cracking operationdescribed herein, preferred cations are hydrogen, ammonium, rare earthand mixtures thereof. Ion exchange is suitably accomplished byconventional contact of the zeolite with a suitable salt solution of thedesired cation such as, for example, the sulfate, chloride or nitrate.

The framework dealuminated faujasitic zeolites suitable for use in thepresent invention are modified in activity by dilution with a matrixcomponent of significant or little catalytic activity. It may be oneproviding a synergistic effect as by large molecule cracking, large porematerial and act as a coke sink. Catalytically active inorganic oxidematrix material is particularly desired because of its porosity,attrition resistance and stability under the cracking reactionconditions encountered particularly in a catalyst cracking operation.Catalysts of the present invention are readily prepared by dispersingthe zeolitic component in a suitable siliceous sol and gelling the solby various means.

The inorganic oxide which serves as a matrix in which the abovecrystalline zeolite is distributed includes silica gel or a cogel ofsilica and a suitable metal oxide. Representative cogels includesilica-alumina, silica-magnesia, silica-zirconia, silica-thoria,silica-beryllia, silica-titania, as well as ternary combinations such assilica-alumina-magnesia, silica-alumina-zirconia andsilica-magnesia-zirconia. Preferred cogels include silica-alumina,silica-zirconia or silica-alumina-zirconia. Particularly preferred is asilica-alumina cogel. The above gels and cogels will generally comprisea major proportion of silica and a minor proportion of theaforementioned oxide or oxides.

Generally the amount of framework dealuminated faujasitic zeolites inthe disclosed catalyst compositions ranges from 1 to 60 weight percentbased on the total weight of the composition; preferably, they rangefrom 5 to 45 weight percent; and, most preferably they range from 5 to40 weight percent. Correspondingly, the amount of matrix will vary from40 to 99 weight percent, based on total weight of said composition;preferably it will vary from 55 to 95 weight percent; most preferablysaid matrix will vary from 60 to 95 weight percent.

Another important aspect of the catalysts of the present invention isthe presence of aluminum compounds. These may be available by virtue oftheir presence within the dealuminated zeolite or by virtue of theirpresence in the particular matrix chosen for compositing with saidzeolites or a combination of both. Alternately they may be provided byincorporation into said composite via dispersion, ion exchange,impregnation and/or deposition by techniques known to those skilled inthe art as incipient wetness impregnation, ion exchange, coating, merelyto name a few pertinent techniques. The amount of alumina incorporatedcan range from 0.01 to 15 weight percent, based on total weight of saidcomposition; preferably, the alumina can vary from 0.01 to 10 weightpercent; most preferably, it can vary from 0.01 to 7 weight percent.

Yet still another important aspect of the catalysts of the presentinvention is the presence of rare earth compounds. These may beavailable by virtue of their presence within the dealuminated zeolite orby virtue of their presence in the particular matrix chosen forcompositing with said zeolites or a combination of both. Alternatelythey may be provided by incorporation into said composite viadispersion, ion exchange, impregnation and/or desposition by techniquesknown to those skilled in the art as incipient wetness impregnation, ionexchange, coating, merely to name a few pertinent techniques. The amountof rare earth incorporated can range from 0.01 to 10 weight percent,expressed as trivalent oxides of same, based on the total weight of saidcomposition; preferably, the rare earth content can vary from 0.01 to 6weight percent; most preferably, it can vary from 0.01 to 4 weightpercent.

In a preferred embodiment the catalyst compositions allow that theinorganic oxide matrix may be combined with a raw or natural clay, acalcined clay, or a clay which has been chemically treated with an acidor an alkali medium or both. Preferred clays are those belonging to thefamilies of clay commonly known as kaolin, bentonite, montmorillonite orhalloysite. Alternately or in addition the inorganic oxide matrix may becombined with weighting or densifying agents including, for example,alumina (corundum), magnesia, beryllia, barium oxide, zirconia and/ortitania. Preferably from 1 to 80 wt % of the matrix comprises aweighting agent, a densifying agent or mixtures thereof selected fromthe group of alumina (corundum) TiO₂, ZrO₂ and clays.

In another preferred embodiment the catalyst compositions of the presentinvention can incorporate noble metals and/or rhenium therein.

A recent advance in the art of catalytic cracking is disclosed in U.S.Pat. No. 4,072,600, the entire contents of which are incorporated hereinby reference. One embodiment of this aforesaid patent teaches that traceamounts of a metal selected from the group consisting of platinum,palladium, iridium, osmium, rhodium, ruthenium, and rhenium when addedto cracking catalysts enhance significantly conversion of carbonmonoxide during the catalyst regeneration operation.

In employing this recent advance to the present invention, the amount ofsaid metal added to the catalysts of the present invention can vary frombetween about 0.01 ppm and about 100 ppm based on total catalystinventory; preferably, 0.01 to 50 ppm by weight; most preferably, 0.01to 5 ppm by weight.

In yet another preferred embodiment the catalyst compositions hereindisclosed can include chromium. The methods of incorporation of chromiumare substantially the same as those disclosed heretofore for both thealuminum and rare earth compounds. The amount of chromium incorporated,expressed as Cr₂ O₃, based on the total weight of said composition, canvary from 0.01 to 1 weight percent chromium; preferably, 0.01 to 0.5weight percent; most preferably 0.01 to 0.3 weight percent.

In accordance with the invention, the composition can be used alone orin combination with a zeolite having a Constraint Index of 1 to 12. Onesuch zeolite is ZSM-5; if the Constraint Index of ZSM-5 is measured atdifferent temperatures, but within the bounds of the limits ofconversion set forth below, it is found to vary but remains within therange of 1 to 12. Cf. Frilette et al., "Catalysis by CrystallineAluminosilicates: Characterization of Intermediate Pore-size Zeolites by`Constraint Index`", Journal of Catalysis, Vol. 67, No. 1, Jan. 1981,pp. 218-221.

The "constraint index" is calculated as follows: ##EQU1##

The constraint index approximates the ratio of the cracking rateconstants for the two hydrocarbons.

It is to be realized that the above constraint index values typicallycharacterize the specified zeolites but that these are the cumulativeresult of several variables used in determination and calculationthereof. Thus, for a given zeolite depending on the temperature employedwithin the range of 550° F. to 950° F., with accompanying conversionbetween 10% and 60%, the constraint index may vary within the indicatedapproximate range of 1 to 12. Likewise, other variables, such as thecrystal size of the zeolite, the presence of possible occludedcontaminants and binders intimately combined with the zeolite may affectthe constraint index. It will accordingly be understood by those skilledin the art that the constraint index, as utilized herein, whileaffording a highly useful means for characterizing the zeolites ofinterest is an approximation, taking into consideration the manner ofits determination, with probability in some instances, of compoundingvariable extremes.

While the above experimental procedure will enable one to achieve thedesired overall conversion of 10 to 60% for most catalyst samples andrepresents preferred conditions, it may occasionally be necessary to usesomewhat more severe conditions for samples of very low activity, suchas those having a very high silica to alumina mole ratio. In thoseinstances, a temperature of up to about 1000° F. and a liquid hourlyspace velocity of less than one, such as 0.1 or less, can be employed inorder to achieve a minimum total conversion of about 10%.

The catalyst compositions of the present invention can be used incatalytic cracking processes. Constant conversion comparisons, relativeto conventional REY cracking catalysts, reveal that the new catalystcompositions disclosed herein yield:

1) significant increases in gasoline volume without significantincreases in research or motor octane (clear). This is in markedcontrast to what has been claimed for prior art USY or DAY containingcracking catalysts. Prior art USY or DAY containing cracking catalysts,which are substantially free of rare earth elements are characterized bytheir ability to significantly increase the research and motor octane ofgasoline produced from catalytic cracking albeit at a yield penalty.

2) significant reductions in C₄ and lighter gas make. This also isdirectionally opposite to what has been claimed for prior art USY or DAYcracking catalysts.

3) significant reductions in coke make. This feature is associated withprior art USY or DAY cracking catalysts provided that they aresubstantially free of rare earth elements. By contrast the desirablefeature of low coke make is evident at all levels of rare earth contentfor the catalyst compositions of this invention, the opposite being truefor prior art USY or DAY cracking catalysts.

4) significant increases in the amount of the more desirable hydrocarbonfraction known as light fuel oil concomitant with reductions in theamount of the less desirable hydrocarbon fraction known as heavy fueloil.

The desirable features associated with the use of the present catalystsin catalytic cracking are graphically shown in FIG. 1 which is discussedabove. The benefits derivable from use of the present catalysts incatalytic cracking are further described in the examples given below.

Another significant feature of the catalysts of the present invention,which renders them particularly useful in catalytic cracking processes,is their catalytic activity/stability relative to state-of-the-art REY,USY and RE-USY containing cracking catalysts. As can be seen graphicallyin FIG. 2 and further in the examples given below catalytic activityincreases and hydrothermal stability improves as rare earth contentincreases. Furthermore it can be seen that at certain rare earthloadings the catalysts of the present invention exhibit superioractivity and hydrothermal stability relative to conventional REYcracking catalysts. Hence certain catalysts of the present inventionwill require lower useage per barrel of fuel relative to commercialcracking catalysts currently in use.

Hydrocarbon charge stocks undergoing cracking in accordance with thisinvention comprise hydrocarbons generally and, in particular, petroleumfractions having an initial boiling range of at least 400° F., a 50%point range of at least 500° F. and an end point range of at least 600°F. Such hydrocarbon fractions include gas oils, residual oils, cyclestocks, whole top crudes and heavy hydrocarbon fractions derived by thedestructive hydrogenation of coal, tar, pitches, asphalts and the like.As will be recognized, the distillation of higher boiling petroleumfractions above about 750° F. must be carried out under vacuum in orderto avoid thermal cracking. The boiling temperatures utilized herein areexpressed in terms of convenience of the boiling point corrected toatmospheric pressure.

Catalytic cracking, in which the catalysts of the invention areemployed, embraces operational conditions including temperature rangesof about 400° F. (204° C.) to 1200° F. (649° C.) and reduced,atmospheric or super atmospheric pressures. The catalytic crackingprocess may be operated batchwise or continuously. The catalyticcracking process can be either fixed bed, moving bed or fluidized bed.The hydrocarbon chargestock flow may be either concurrent orcountercurrent to the catalyst flow. The process of the invention isapplicable to fluid catalytic cracking (FCC) processes. Briefly, in theFCC process, the catalyst is in the form of microspheres, which act as afluid when suspended in oil, vapor or gas. The hydrocarbons contact thefluidized catalysts and are catalytically cracked to lighter products.Deactivation of the catalyst by coke necessitates regeneration of thecoked catalyst in the regenerator of an FCC unit. Although the designand construction of individual FCC units can vary, the essentialelements of an FCC unit are illustrated in U.S. Pat. No. 4,368,114 whichis incorporated herein by reference.

The process of the invention is also directed to moving bed catalyticcracking units having moving bed catalyst regeneration units associatedtherewith. Thermofor catalytic cracking (TCC) and Houdriflow catalyticcracking are representative of such moving bed cracking and moving bedregeneration units. The catalyst is generally maintained as adownflowing moving bed of catalyst. The catalysts may be disposed of anannular bed, with radial, in or out, gas flow. The moving catalyst bedmay have the cross section of a circle or a rectangle with gas flow fromthe lower portion of the catalyst bed to the upper or the reverse.Alternatively, gas flow may be across the moving bed of catalyst, orsome combination of cross-flow, downflow and upflow. Generally, althoughthe catalyst from the moving bed of a catalytic cracking unit is usuallystripped before being sent to the regenerator, there is usually a smallamount of hydrocarbon, and hydrogen-containing coke, contained on thecatalyst. This material is relatively easy to burn, and is usuallyburned from the catalyst in the top 5 to 10% of the moving bed catalystregeneration unit. Usually more severe conditions are necessary tocompletely remove the more refractive, relatively hydrogen-free cokethat remains on the catalyst after hydrocarbons are burned off, soprogressively more severe operating conditions are experienced in thelower portions of the moving bed. These conditions may be increasedtemperature, increased oxygen concentration, or both.

After cracking, the resulting product gas is compressed and theresulting products may suitably be separated from the remainingcomponents by conventional means such as adsorption, distillation, etc.

The following comparative examples serve to illustrate the compositionand process for preparing the catalysts of this invention and theadvantages of their use in hydrocarbon processing, more particularlycatalytic cracking, without limiting the same.

EXAMPLE 1

To prepare the catalysts of the present invention, a typical formulationis herewith described. Two solutions were prepared; Solution A contained41.67 parts sodium silicate (SiO₂ /Na₂ O ratio of 3.22), 3.00 partsDavison Z-14US ultrastable Y zeolite (USY), 9.26 parts alpha-alumina(corundum), 1.92 parts NaOH, and 40.93 parts H₂ O. Solution B contained3.47 parts Al₂ (SO₄)₃, 5.87 parts H₂ SO₄, and 90.66 parts H₂ O. Thesetwo solutions were cooled to 60° F. and combined by mixing through anozzle such that the pH was maintained at 8.4 plus or minus 0.2. Theresultant mixture was passed through a 5 foot column of oil at roomtemperature during which time the combined solutions formed sphericalparticles less than 1/2 inch in diameter and gelled prior to contactwith water. These rigid particles were then separated from and washedessentially free of residual oil. The particles were then contacted witha solution of 1.5% wt Al₂ (SO₄)₃ for a total of 18 hours, using newsolution every two hours and subsequently washed until no sulfate couldbe detected in the effluent by testing with barium chloride solution.Next they were contacted with a solution containing 0.75% wt RECl₃.6H₂ O(Rare Earth Chloride, Code 1433, manufactured by Davison SpecialtyChemical Co.) for a period of 6 hours and washed with water until noresidual chloride could be detected in the effluent by testing withsilver nitrate solution. The catalyst was placed in slotted trays anddried in an approximately 100% steam atmosphere to a final temperatureof 320° F. for a minimum of 15 minutes. The catalyst was furthersubjected to steam calcination or tempering for 12 hours at 1290° F. inapproximately 95% steam/5% air at atmospheric pressure. Physical andchemical properties of the catalyst are shown in Table 1, along with theproperties of two commercial REY catalysts designated as Catalyst A andCatalyst B.

                  TABLE 1                                                         ______________________________________                                                     Example 1                                                                             Catalyst A                                                                              Catalyst B                                     ______________________________________                                        Chemical                                                                      Silica, % wt   57.0      50.5      48.8                                       Alumina, % wt  42.0      42.8      40.4                                       RE.sub.2 O.sub.3, % wt                                                                       1.08      2.20      2.90                                       Na, % wt       0.13      0.16      0.40                                       Ash, % wt @ 1000° C.                                                                  98.3      97.2      96.9                                       Physical                                                                      Surface Area, m.sup.2 /g                                                                     132       165       149                                        Real Density, g/cc                                                                           2.73      2.77      ND                                         Particle Density, g/cc                                                                       1.32      1.37      ND                                         Pore Volume, cc/g                                                                            0.39      0.36      ND                                         Avg. Pore Diameter, Ang-                                                                     118       89        ND                                         stroms                                                                        Diffusivity, cm.sup.2 /                                                                      31        20        ND                                         sec × 1000                                                              Unit Cell Size, Angstroms                                                                    24.42     24.62     ND                                         ______________________________________                                         ND = Not Determined                                                      

EXAMPLE 2

The catalyst of example 1 was evaluated cracking Mid-Continent PipelineGas Oil (MCPLGO) in a fixed bed reactor. Vapors of the gas oil arepassed through the catalyst at 925° F. substantially at atmosphericpressure at a feed rate of 3 volumes of liquid oil per volume ofcatalyst per hour for 10 minutes. The method of measuring the instantcatalyst was to compare the various product yields obtained with suchcatalyst with yields of the same products given by a commercial REYcatalyst. The differences (Delta values) shown hereinafter represent theyields given by the present catalyst minus yields given by the REYcatalyst. In addition, samples were steam deactivated for 9 and 18 hoursin a 100% steam atmosphere at 1300° F. and 40 psig prior to catalyticevaluation. The results are presented graphically in FIG. 1 and atconstant 60 volume percent conversion in Table 2. As is readilyapparent, the catalyst of the present invention yields at constantconversion, significantly more gasoline and light fuel oil whilereducing coke and C.sub. 4⁻ gas yields.

                  TABLE 2                                                         ______________________________________                                        Mid-Continent Gas Oil                                                                                   EXAMPLE 1                                           60 Vol % Conversion                                                                              REY    Δ                                             ______________________________________                                        C.sub.5 .sup.+ Gasoline, % Vol                                                                   48.8   +2.7                                                Total C.sub.4 's, % Vol                                                                          12.5   -0.9                                                C.sub.3 .sup.- Gas, % Wt                                                                         6.2    -0.7                                                Coke, % Wt         2.9    -1.1                                                LFO, % Wt          33.7   +1.1                                                HFO, % Wt          7.4    -1.0                                                Potential Alkylate, % Vol                                                                        14.9   +1.4                                                G + D + PA, % Vol  97.4   +5.2                                                ______________________________________                                    

EXAMPLE 3

To study the contribution of the aluminum exchange on the catalyst, twocatalysts were prepared by the technique described in Example 1, exceptthat one sample was treated for 24 hours in NH₄ OH followed by nine2-hour exchanges with 2% wt (NH₄)₂ SO₄ rather than 1.5% wt Al₂ (SO₄)₃.Both catalysts were then washed sulfate free and dried without rareearth exchange, followed by steam tempering as in Example 1. Thechemical/physical properties are listed in Table 3. These catalysts weresteam deactivated for 9 hours in a 100% steam atmosphere at 1300° F. and40 psig and tested catalytically at the same conditions stated inExample 2; the results are reported in Table 4. The catalyst of thepresent invention shows higher initial activity, and better retention ofactivity after steaming

                  TABLE 3                                                         ______________________________________                                        Exchange Solution  Aluminum   Ammonium                                        ______________________________________                                        Chemical                                                                      Silica, % Wt       52.0       53.5                                            Alumina, % Wt      45.2       44.4                                            RE.sub.2 O.sub.3, % Wt                                                                           0          0                                               Na, % Wt           0.29       0.35                                            Ash, % Wt @ 1000° C.                                                                      98.9       98.7                                            Physical                                                                      Surface Area, m.sup.2 /g                                                                         138        155                                             Real Density, g/cc 2.77       2.77                                            Particle Density, g/cc                                                                           1.22       1.01                                            Pore Volume, cc/g  0.46       0.63                                            Avg. Pore Diameter, Angstroms                                                                    133        164                                             Diffusivity, cm.sup.2 /sec × 1000                                                          64         59                                              Unit Cell Size, Angstroms                                                                        24.33      24.36                                           ______________________________________                                    

                  TABLE 4                                                         ______________________________________                                                         Unsteamed                                                                              Steamed                                                              Alum  NH.sub.4                                                                             ALUM    NH.sub.4                                ______________________________________                                        Conversion, % Vol  64.9    50.9   29.0  18.3                                  C.sub.5 .sup.+ Gasoline, % Vol                                                                   51.7    43.7   26.5  17.7                                  Total C.sub.4 's, % Vol                                                                          15.5    9.1    3.8   1.2                                   C.sub.3 .sup.- Gas, % Wt                                                                         7.0     4.9    2.6   1.8                                   Coke, % Wt         1.91    1.58   0.95  0.91                                  Alkylate, % Vol    22.7    14.6   7.7   3.2                                   C.sub.5 .sup.+ Gasoline + Alkylate, % Vol                                                        74.4    58.3   34.2  20.8                                  RON + 0, C.sub.5 .sup.+ Gasoline                                                                 88.5    85.8   87.5  86.4                                  RON + 0, C.sub.5 .sup.+ Gasoline + Alkylate                                                      90.2    87.9   89.0  87.6                                  LFO, % Wt          32.2    41.1   52.7  56.8                                  HFO, % Wt          4.5     8.9    18.1  24.2                                  G + D, % Wt        76.3    78.6   75.8  72.3                                  ______________________________________                                    

EXAMPLE 4

To study the contribution of rare earth on catalytic performance,catalysts were prepared at increasing levels of rare earth. Thechemical/physical properties are listed in Table 5. The results ofcatalytic evaluations are given in Table 6. In addition, the catalysts'hydrothermal stability was evaluated by deactivating the catalysts for 9and 18 hours in a 100% steam atmosphere at 1300° F. and 40 psig prior tocatalytic evaluation. The results are shown in FIG. 2. As is readilyapparent, the importance of sufficient rare earth on the final catalystis seen in the effect on hydrothermal stability. Hydrothermal stabilityis improved with increasing rare earth content. It is further seen thatthe activity/stability of the catalyst of this invention at sufficientlyhigh rare earth levels exceeds that of a conventional non-dealuminatedREY catalyst.

                  TABLE 5                                                         ______________________________________                                        Chemical                                                                      Silica, % Wt     52.0    52.0    52.0  51.0                                   Alumina, % Wt    45.2    44.8    44.8  44.0                                   RE.sub.2 O.sub.3, % Wt                                                                         0       0.4     0.7   1.1                                    Na, % Wt         .10     .12     .13   .14                                    Ash, % Wt @ 1000° C.                                                                    98.9    98.9    99.2  98.5                                   Physical                                                                      Surface Area, m.sup.2 /g                                                                       138     141     145   148                                    Real Density, g/cc                                                                             2.77    2.77    2.78  2.79                                   Particle Density, g/cc                                                                         1.22    1.25    1.20  1.22                                   Pore Volume, cc/g                                                                              0.45    0.44    0.47  0.46                                   Avg. Pore Diameter, Ang-                                                                       133     125     130   128                                    stroms                                                                        Diffusivity, cm.sup.2 /sec × 1000                                                        64      69      68    66                                     Unit Cell Size, Angstroms                                                                      24.33   24.35   24.41 24.38                                  ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Rare Earth Level, % Wt                                                                            0      0.4     0.7  1.1                                   Conversion, % Vol   64.9   68.4    70.2 71.4                                  C.sub.5 .sup.+ Gasoline, % Vol                                                                    51.7   55.8    57.4 57.7                                  Total C.sub.4, % Vol                                                                              15.5   14.8    14.7 15.4                                  C.sub.3 .sup.- Gas, % Wt                                                                          7.0    7.3     7.5  7.6                                   Coke, % Wt          1.91   2.10    2.36 2.39                                  Alkylate, % Vol     22.7   21.1    21.2 21.3                                  C.sub.5 .sup.+ Gasoline + Alkylate, % Vol                                                         74.4   76.9    78.6 79.0                                  RON + 0, C.sub.5 .sup.+ Gasoline                                                                  88.5   86.1    86.4 86.1                                  RON + 0, C.sub.5 .sup.+ Gasoline + Alkylate                                                       90.2   88.3    88.5 88.2                                  LFO, % Wt           32.2   29.6    28.2 27.3                                  HFO, % Wt           4.5    3.8     3.5  3.3                                   G + D, % Wt         76.3   77.0    76.9 76.5                                  ______________________________________                                    

EXAMPLE 5

To see if this catalyst was chargestock specific, the catalyst ofExample 1 was evaluated cracking two additional type crudes. The resultsof this evaluation are given in Table 7. In all cases, the catalyst ofthe present invention shows improved liquid yields at the expense of gasand coke. As can be seen from the properties in Table 8, the heavier thefeed, the more effective in the catalyst of this invention.

                  TABLE 7                                                         ______________________________________                                                   Altona      Frontignan                                                        Mixed Feed(1)                                                                             Gas Oil(2)                                             60 Vol % Conversion                                                                        REY    EXAMPLE 1  REY  EXAMPLE 1                                 ______________________________________                                        C.sub.5 .sup.+ Gasoline, % Vol                                                             47.5   +2.4       43.2 +4.2                                      C.sub.5 .sup.+ Gasoline,                                                                   85.4   -0.9       88.5 -1.5                                      RON + 0                                                                       Total C.sub.4 's, % Vol                                                                    13.1   -1.0       11.9 +0.1                                      C.sub.3 .sup.- Gas, % Wt                                                                   6.3    -0.7       8.3  -1.3                                      Coke, % Wt   2.3    -1.0       5.9  -2.3                                      LFO, % Wt    31.5   +1.7       30.0 +1.4                                      HFO, % Wt    10.0   -1.7       11.9 -1.1                                      Potential Alkylate, %                                                                      19.7   +0.4       13.8 +2.2                                      Vol                                                                           G + D + PA, % Vol                                                                          98.7   +4.5       87.0 +7.8                                      ______________________________________                                         (1) Derived from Gippsland Crude                                              (2) Derived from Middle East and North African Crudes                    

                  TABLE 8                                                         ______________________________________                                        Chargestock Properties                                                                        Front-   Altona(3)                                                     JSHGO  ignan(2) Mixed     (4)                                                 (1)    GasOil   Feed      MCPLGO                                     ______________________________________                                        API Gravity                                                                              24.3     23.2     34.6    29.0                                     Specific Gravity,                                                                        0.9082   .9147    0.8519  .8816                                    60° F.                                                                 Pour Point, °F.                                                                   95       100      105     80                                       KV @ 100° C., cs                                                                  3.62     5.51     2.995   3.51                                     Refractive Index,                                                                        1.5081   1.4902   1.46059 1.4716                                   70° C.                                                                 Aniline Point                                                                            171      172      202.7   178                                      Bromine Number                                                                           4.2      8.8      2.2     1.9                                      CCR, wt %  0.29     0.36     0.21    0.48                                     Sulfur, wt %                                                                             1.87     1.62     0.145   0.56                                     Hydrogen, wt %                                                                           12.23    12.55    13.30   12.79                                    Nitrogen, % wt                                                                           0.03     0.11     0.04    0.07                                     Nitrogen, basic,                                                                         327      --       109     144                                      ppm                                                                           Molecular Weight                                                                         358      --       306     --                                       Nickel, ppm                                                                              0.15     .39      0.27                                             Vanadium, ppm                                                                            0.18     .59      0.10                                             Iron, ppm  9.3      --       3.13                                             Copper, ppm                                                                              0.10     --       0.10                                             Distillation                                                                  (D1160), ° F.                                                          IBP        414      --       422     434                                      5%, vol    548      --       561     550                                      10%        614      627      608     577                                      20%        667      --       667     604                                      30%        701      741      703     624                                      40%        733      --       733     658                                      50%        767      805      756     700                                      60%        801      --       778     743                                      70%        839      864      802     789                                      80%        877      --       831     837                                      90%        924      950      882     888                                      95%        956      --       929     924                                      EP                  --       937     --                                       Composition,                                                                  wt %                                                                          Paraffins  23.5     49.4     60      30.7                                     Naphthenes 32.0     29.2     15      35.7                                     Aromatics  44.5     21.4     25      33.6                                     ______________________________________                                         (1) Joliet Sour Heavy Gas Oil                                                 (2) Derived from Middle East and North African Crudes                         (3) Derived from Gippsland Crude                                              (4) MidContinent Pipeline Gas Oil                                        

EXAMPLE 6

A catalyst was prepared in the identical manner of Example 1, exceptafter the rare earth exchange and final wash, the undried particles weremixed in a high shear mixer with sufficient deionized water to form apumpable slurry and passed through a homogenizer. The homogeneous slurrywas then fed to a spray dryer and particles typical in size to thoseused in FCC were prepared. This catalyst which contained 12% USY wassubsequently steam deactivated at 1450° F. for 10 hours at 0 psig in a45% steam/55% air atmosphere. For comparison, a catalyst not of thisinvention, containing 12% calcined REY, was prepared in a similar mannerto this example and also subjected to steam deactivation.

EXAMPLE 7

The catalysts prepared in Example 6 were evaluated in a fixed-fluidizedbench unit cracking Joliet Sour Heavy Gas Oil (JSHGO) at 960° F. with afeed rate of 12 to 24 grams of liquid oil per gram of catalyst per hourand a run time of 1 minute. The results are shown in Table 9. As can beseen, the catalyst of the present invention results in increasedgasoline yield and lower coke and C₄ ⁻ gas make.

                  TABLE 9                                                         ______________________________________                                                           Example 6  REY                                             ______________________________________                                        Conversion, % Vol    65.0         65.0                                        C.sub.5 .sup.+ Gasoline, % Vol                                                                     51.2         48.4                                        Total C.sub.4 's, % Vol                                                                            15.5         16.0                                        C.sub.3 .sup.- Gas, % Wt                                                                           7.4          8.3                                         Coke, % Wt           3.26         4.00                                        Alkylate, % Vol      24.2         24.7                                        C.sub.5 .sup.+ Gasoline + Alkylate, % Vol                                                          75.4         73.1                                        LFO, % Wt            30.1         30.9                                        HFO, % Wt            7.1          6.3                                         G + D, % Wt          72.3         71.2                                        ______________________________________                                    

EXAMPLE 8

A catalyst of the present invention was prepared according to theprocedure of Example 1, except the finished catalyst contained 20% USYvs 12% USY in Example 1. The chemical/physical properties are shown inTable 10. This catalyst also shows the advantage in increased gasolineyield and lower coke and gas over currently available REY catalysts.

                  TABLE 10                                                        ______________________________________                                        Silica, % Wt          66.0                                                    Alumina, % Wt         40.4                                                    RE.sub.2 O.sub.3, % Wt                                                                              1.42                                                    Na, % Wt              0.17                                                    Ash, % Wt @ 1000° C.                                                                         99.0                                                    Surface Area, m.sup.2 /g                                                                            201                                                     Real Density, g/cc    2.67                                                    Particle Density, g/cc                                                                              1.34                                                    Pore Volume, cc/g     0.37                                                    Avg. Pore Diameter, Angstroms                                                                       74                                                      Diffusivity, cm.sup.2 /sec × 1000                                                             22                                                      Unit Cell Size, Angstroms                                                                           24.44                                                   ______________________________________                                    

EXAMPLE 9

A catalyst was prepared in the identical manner of Example 1, exceptthat 0.6 parts CrK(SO₄)2.12H₂ O was added to solution B prior to mixingwith solution A. Analysis of the finished catalyst was essentially thesame as in Example 1, with the addition of 0.13% wt Cr. Catalyticevaluation showed identical performance to the catalyst of Example 1.

EXAMPLE 10

A catalyst was prepared in the identical manner of Example 1, exceptthat the particles were contacted with a solution containing Pt(NH₃)₄Cl₂ for a period of 1 hour subsequent to the final water wash followingthe rare earth exchange. Chemical analysis showed approximately 5 ppm Pton the finished catalyst. Catalytic evaluation showed identicalperformance to the catalyst of Example 1.

EXAMPLE 11

The catalyst of Example 1 was evaluated cracking Gippsland reduced crudeand compared against a commercial REY catalyst. The results are shown inTable 11. As can be seen, the use of the catalyst of the presentinvention is particularly advantageous when using heavy feedstocks.Significant gains in liquid products are made at the expense of C₄ ⁻gases and coke.

                  TABLE 11                                                        ______________________________________                                        Gippsland Atmospheric Resid.sup.1                                                              REY     EXAMPLE 1   Δ                                  ______________________________________                                        Conversion, % Vol                                                                              70.0    70.0        --                                       C.sub.5 + Gasoline, % Vol                                                                      51.2    58.3        +7.1                                     Total C.sub.4 's, % Vol                                                                        17.3    14.8        -2.5                                     C.sub.3 .sup.- Gas, % Wt                                                                       7.3     5.4         -1.9                                     Coke, % Wt       5.8     3.4         -2.4                                     C.sub.3 =, % Vol 5.1     5.3         +0.2                                     C.sub.4 =, % Vol 4.4     5.4         +1.0                                     iC.sub.4, % Vol  9.6     7.1         -2.5                                     Alkylate, % Vol  15.7    17.8        +2.1                                     Gasoline + Alkylate, % Vol                                                                     66.9    76.1        +9.2                                     Outside iC.sub.4 Req'd, % Vol                                                                  1.6     5.4         +3.8                                     ______________________________________                                         .sup.(1) Run Conditions: 875° F., 4C/O, 1.5 LHSV.                 

what is claimed is:
 1. A process for the catalytic cracking of ahydrocarbon by contact of said hydrocarbon with a catalytic crackingcatalyst at catalytic cracking conditions to produce cracked products,characterized by use of a catalyst composition comprising:1 to 60 weightpercent framework dealuminated Y zeolite, based on the total weight ofthe composition; 40 to 99 weight percent of a matrix, based on the totalweight of said composition; 0.01 to 15 weight percent aluminaincorporated into said catalyst composition via ion exchange, based onthe total weight of said composition; 0.01 to 10 weight percent rareearth, expressed as the oxides of same, based on the total weight ofsaid composition, dispersed, impregnated or deposited in a composite ofsaid zeolite and said matrix.
 2. The process of claim 1 wherein from 1to 80 weight percent of the matrix is a weighting agent and/or adensifying agent selected from alumina (corundum), TiO₂, ZrO₂ and clays.3. The process of claim 1 wherein the catalyst composition furthercomprises 0.01 to 1 pbw chromium, expressed as Cr₂ O₃.
 4. The process ofclaim 1 wherein the catalyst composition further comprises 1 to 5000 ppmby weight of at least one noble metal and/or rhenium.
 5. The process ofclaim 1 wherein the catalyst composition has an alkali metal content of0.0001 to 1.0 weight percent.
 6. The process of claim 1 wherein thesilica:alumina molar ratio of the framework dealuminated zeolite Y isfrom 5 to
 100. 7. The process of claim 1 wherein said zeolite is in thehydrogen, rare-earth or ammonium exchanged form.
 8. The process of claim1 wherein said rare earth is lanthanum, cerium or mixtures thereofand/or any element of the lanthanide series of the periodic chart ofelements.
 9. The process of claim 1 wherein said matrix is SiO₂, Al₂ O₃,SiO₂ -Al₂ O₃, TiO₂ ZrO₂ and/or clay.
 10. The process of claim 1 whereinthe unit cell size, as determined by x-ray diffraction, of the zeolitein the finished catalyst is from about 24.25A to about 24.55A.
 11. Theprocess of claim 1 wherein the catalyst composition further comprises azeolite having a constraint index of 1 to
 12. 12. The process of claim 1wherein the feedstock comprises at least 50% wt. atmospheric resid. 13.The process of claim 1 wherein the cracking process is a fluidized-bedprocess.
 14. The process of claim 1 wherein the cracking process is amoving-bed process.
 15. A process for the catalytic cracking of ahydrocarbon by contact of said hydrocarbon with a catalytic crackingcatalyst at catalytic cracking conditions to produce cracked products,characterized by use of an aluminum and rare earth exchanged, frameworkdealuminated zeolite cracking catalyst comprising:1 to 60 weight percentframework dealuminated Y zeolite having a framework silica:alumina molarratio of 5:1 to 100:1; 0.01 to 15 weight percent alumina added to saidcatalyst via aluminum exchange; 0.01 to 10 weight percent rare earthoxides; and 40 to 99 weight percent matrix.
 16. The process of claim 1wherein the Y zeolite is an ultrastable Y (USY) zeolite.
 17. The processof claim 15 wherein the Y zeolite is an ultrastable Y (USY) zeolite. 18.The process of claim 1 wherein the rare earth content of the crackingcatalyst is 0.4 to 1.4 weight percent.
 19. The process of claim 15wherein the rare earth content of the cracking catalyst is 0.4 to 1.4weight percent.